The present invention relates to sealing large area display structures, and, more particularly, to sealing tiled OLED display structures.
Electronic display structures are devices that produce patterns of light in response to electrical signals. Different types of display materials may be used for providing the patterns of light. Display structures in which the display materials generate light are known as emissive displays. Emissive displays may be formed using display materials such as organic light emitting diode (OLED) materials. Other types of emissive displays include plasma displays, field emissive displays and electroluminescent displays. Display structures in which the display materials pass or reflect light rather than generate light are known as light-valves. Liquid crystal displays (LCDs) are one form of a light-valve type display structure.
Rather than building a single large electronic display structure (monolithic display), electronic display structures may be mounted adjacent to each other to form tiled displays. A tiled display may function as a single display of a larger size. Tiling of display structures allows for flexibility in size and shape of displays. Tiling is not subject to many of the problems that limit the size of monolithic display technologies. The complexity law does not apply because the basic unit of manufacture in tiled displays may be less complex than large monolithic displays. The size law is not a limiting factor because the basic unit of manufacture is relatively small. Tiled displays obey a scaling-law which is not exponential but linear with display area. This fundamentally different scaling behavior is one advantage of tile technology which results in reduced manufacturing costs.
It is desirable to minimize visibility of the junction between adjacent display structures included in a tiled display. Each individual tile or display structure has a front display surface on which an image is formed. In many cases this surface is protected with a glass cover. Tiles are fastened in a matter for their front glass covers to be adjacent to each other.
Display structures are typically fabricated by coupling top and bottom substrates together. Because many display materials require that a vacuum, moisture or hermetic seal be maintained around the pixels of the display structure, it is desirable that the mechanical junction between top and bottom substrates also serve as a sealing mechanism. The integrity of a sealing mechanism may be critical for predictable device performance and to ensure a predictable device lifetime.
The patterns of light formed by display structures in response to electrical signals are formed by individual display elements or pixels. To independently control the light corresponding to each pixel, each pixel may be addressed using electrical signals. For a display structure having top and bottom substrates, it may be desirable to couple these electrical signals between the substrates. It is often difficult to couple these signals to the display structure due to the large number of signals and the desire to simultaneously seal the display material of the display structure.
The visibility of seams, the need to couple electrical signals, and the need to seal a display provide conflicting display manufacturing goals. A thicker and more robust seal at a tile boundary may increase the width of the seam between tiles and result in the seam becoming more visible.
To overcome the shortcomings of conventional methods of sealing tiled display structures, a new method of sealing tiled display structures is provided.
The present invention provides an electronic display structure comprising a display module and an area seal. The display module includes a first substrate having a plurality of column electrodes. Each of a plurality of portions of a display material are coupled to one of the plurality of column electrodes and to one of a plurality of row electrodes. The area seal is formed upon the first substrate and encapsulates the row electrodes, the column electrodes, and the portions of display material.
According to one aspect of the present invention, the area seal comprises an anisotropically conductive structure for encapsulating the plurality of row electrodes, the plurality of column electrodes, and the plurality of portions of the display material, and for coupling each of the plurality of row and column electrodes to a respective signal line.
According to another aspect of the present invention, a processing step of forming the anisotropically conductive structure is used to both seal the electronic display structure and to couple the display module to the circuit module.
According to another aspect of the present invention, the electronic display structure also includes a circuit module including plurality of signal lines each corresponding to one of the plurality of row and column electrodes and the anisotropically conductive structure seals the circuit module and the display module, adheres the circuit module to the display module, and couples each of the plurality of row and column electrodes to its respective signal line.
According to another aspect of the present invention, the anisotropically conductive structure is substantially black.
According to another aspect of the present invention, the plurality of row electrodes is coupled to and encapsulates each of the plurality of portions of the display material.
According to another aspect of the present invention, the electronic display structure comprises a band seal spanning from the display module to the circuit module and extending around the perimeter of the circuit and display modules.
According to another aspect of the present invention, the display material includes an organic electroluminescent material.
According to another aspect of the present invention, a bead seal couples an outer area of the display module to an outer area of the circuit module and a masking layer acts to hide the bead seal when the display structure is viewed from the first surface of the substrate.
According to another aspect of the present invention, the bead seal occupies an area less than one-half of the gap between pixels to minimize the visual perception of seams between adjacent display tiles.